Methods for producing silicon nitride films and silicon oxynitride films by thermal chemical vapor deposition

Abstract

Silicon nitride film is formed on substrate (112) by feeding trisilylamine and ammonia into a CVD reaction chamber (11) that contains a substrate (112). The ammonia gas/trisilylamine gas flow rate ratio is set to a value of at least about 10 and/or the thermal CVD reaction is run at a temperature no greater than about 600° C. Silicon oxynitride is obtained by introducing an oxygen source gas into the CVD reaction chamber (11). This method avoids the production of ammonium chloride and/or the incorporation of carbonaceous contaminants which are detrimental to the quality of the deposited film.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] This invention relates to methods for producing silicon nitride films and silicon oxynitride films. More particularly, this invention relates to methods for producing silicon nitride films and silicon oxynitride films by thermal chemical vapor deposition (thermal CVD). [0003] 2. Description of the Prior Art [0004] Silicon nitride films have excellent barrier properties and an excellent oxidation resistance and as a consequence are used in the fabrication of semiconductor devices, for example, as an etch-stop layer, barrier layer, or gate dielectric layer, and in oxide / nitride stacks. [0005] Plasma-enhanced CVD (PECVD) and low-pressure CVD (LPCVD) are the methods primarily used at the present time to form silicon nitride films. [0006] PECVD is typically carried out by introducing a silicon source (typically silane) and a nitrogen source (typically ammonia, but more recently nitrogen) between a pair of parallel plate ...

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Benefits of technology

[0012] As the result of extensive investigations directed to addressing the issues described hereabove, the present inventors found that trisilylamine, aside from its lack of chlorine and carbon, reacts with ammonia to produce high-quality silicon nitride and reacts with ammonia and an oxygen-containing gas to produce high-quality silicon oxynitride. These reactions are also not accompanied by the appearance of reaction by-products downstream from the reaction chamber. The inventors also discovered that the ammonia: trisilylamine feed flow rate ratio into the reaction chamber during the production of silicon nitride film by the reaction of trisilylamine with ammonia influences the compositional stability of the resulting silicon nitride film. The inventors further discovered that the reaction temperature (film formation temperature) during the production of silicon nitride film by the reaction of trisilylamine with ammonia influences the step coverage afforded by the silicon nitride film product. The present invention is based on these discoveries.

Problems solved by technology

The silicon nitride films formed in this manner by PECVD typically do not have a stoichiometric composition and are also hydrogen rich and accordingly exhibit a low film density, a poor step coverage, a fast etching rate, and a poor thermal stability.

However, ammonium chloride is produced as a by-product in the reaction of dichlorosilane and gaseous ammonia in this LPCVD procedure: this ammonium chloride accumulates in and clogs the reactor exhaust lines and also deposits on the wafer.

This problem also occurs when the aforementioned prior art precursors are used to produce silicon oxynitride films (with the same precursors, nitrogen containing gases plus an oxygen containing gas, which are films that have the same properties and applications as silicon nitride films.

However, this article does not go beyond reporting on the silicon nitride growth mechanism, nor does it provide any evaluation of the properties of the produced silicon nitride films.

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